Fibre-rich diet attenuates chemotherapy-related neuroinflammation in mice

The gastrointestinal microbiota has received increasing recognition as a key mediator of neurological conditions with neuroinflammatory features, through its production of the bioactive metabolites, short-chain fatty acids (SCFAs). Although neuroinflammation is a hallmark shared by the neuropsychological complications of chemotherapy (including cognitive impairment, fatigue and depression), the use of microbial-based therapeutics has not previously been studied in this setting. Therefore, we aimed to investigate the effect of a high fibre diet known to modulate the microbiota, and its associated metabolome, on neuroinflammation caused by the common chemotherapeutic agent 5-fluorouracil (5-FU). Twenty-four female C57Bl/6 mice were treated with 5-FU (400 mg/kg, intraperitoneal, i.p.) or vehicle control, with or without a high fibre diet (constituting amylose starch; 4.7 % crude fibre content), given one week prior to 5-FU and until study completion (16 days after 5-FU). Faecal pellets were collected longitudinally for 16S rRNA gene sequencing and terminal SCFA concentrations of the caecal contents were quantified using gas chromatography-mass spectrometry (GC-MS). Neuroinflammation was determined by immunofluorescent analysis of astrocyte density (GFAP). The high fibre diet significantly altered gut microbiota composition, increasing the abundance of Bacteroidaceae and Akkermansiaceae (p < 0.0001 and p = 0.0179) whilst increasing the production of propionate (p = 0.0097). In the context of 5-FU, the diet reduced GFAP expression in the CA1 region of the hippocampus (p < 0.0001) as well as the midbrain (p = 0.0216). Astrocyte density negatively correlated with propionate concentrations and the abundance of Bacteroidaceae and Akkermansiaceae, suggesting a relationship between neuroinflammatory and gastrointestinal markers in this model. This study provides the first evidence of the neuroprotective effects of fibre via dietary intake in alleviating the neuroimmune changes seen in response to systemically administered 5-FU, indicating that the microbiota-gut-brain axis is a targetable mediator to reduce the neurotoxic effects of chemotherapy treatment.

5-Fluorouracil Induces an Acute Reduction in Neurogenesis and Persistent Neuroinflammation in a Mouse Model of the Neuropsychological Complications of Chemotherapy

The neuropsychological symptoms associated with chemotherapy treatment remain a major challenge with their prevention hampered by insufficient understanding of pathophysiology. While long-term neuroimmune changes have been identified as a hallmark feature shared by neurological symptoms, the exact timeline of mechanistic events preceding neuroinflammation, and the relationship between the glial cells driving this neuroinflammatory response, remain unclear. We therefore aimed to longitudinally characterize the neuroimmunological changes following systemic 5-fluorouracil (5-FU) treatment to gain insight into the timeline of events preceding the well-documented chronic neuroinflammation seen following chemotherapy. Eighteen female C57Bl/6 mice received a single intraperitoneal dose of 5-FU and groups were killed at days 1 and 2 (acute timepoint), days 4 and 8 (subacute timepoint), and days 16 and 32 (chronic timepoint). A further six mice were administered with vehicle control with tissues collected from three mice on day 1 and day 32 of the study. The expression of key genes of interest, BCL2, BDNF, TIMP1, MMP-9, MMP-2, TNFα, IL-1β, and IL-6R were assessed using real time polymerase chain reaction. Levels of neurogenesis were determined through immunofluorescent staining of doublecortin (DCX). The density of microglia and astrocytes were assessed using immunofluorescence staining of Iba1 and GFAP respectively. 5-FU treatment caused significant decreases to DCX staining at acute timepoints (p = 0.0030) which was positively correlated with BCL2 expression levels. An increase to microglial density was observed in the prefrontal cortex (p = 0.0256), CA3 region (p = 0.0283), and dentate gyrus (p = 0.0052) of the hippocampus at acute timepoints. 5-FU caused increases to astrocyte density, across multiple brains regions, at subacute and chronic timepoints which were positively correlated with TNFα, TIMP-1, MMP-2, and IL-6R expression. This study has identified acute objective neuroinflammatory changes suggesting that the role of early intervention should be explored to prevent the development of neuropsychological deficits in the longer-term following chemotherapy.

Validation and reliability testing of a rating scale for objective assessment of performance in laparoscopic appendicectomy surgery

Backgrounds

To achieve a competency‐based training paradigm, the ability to obtain reliable and valid quantitative assessments of intraoperative performance is required. Through this, weaknesses can be identified and practiced, and competency assessed. This study aimed to determine the validity and reliability an objective evaluation tool for assessment of performance in laparoscopic appendicectomy (LA).

Methods

A prospective single‐blinded observational study design was used. Videos of inexperienced (performed <10 LAs) and experienced (performed >100 LAs) surgeons performing LA surgery were collected. Surgical performance during each recording was rated by two independent, blinded expert surgeons using the LA Rating Scale (LARS) and the modified Objective Structured Assessment of Technical Skill (OSATS) scale.

Results

The intraclass correlation coefficient (ICC) for LARS was 0.95 (95%CI 0.83–0.98). The ICC for each step ranged from 0.48 to 0.90, and the test–retest ICC for LARS was 0.91 (95%CI 0.69–0.98). Significant differences (P < 0.001) between median performance scores as rated by LARS were observed between the inexperienced and experienced surgeons. A Spearman's correlation coefficient of 0.87 (P < 0.001) was observed between LARS performance scores and modified OSATS scores.

Conclusion

LARS demonstrated excellent inter‐rater and test–retest reliability, and construct and concurrent validity and can be used to quantitatively evaluate performance during LA. This can potentially allow specific weaknesses to be identified and improved upon through deliberate practice. Progress can be tracked through re‐evaluation and scores of expert surgeons can be used as performance goals for credentialing in LA.

Development of a rating scale for objective assessment of performance in laparoscopic appendicectomy surgery

Backgrounds

Laparoscopic appendicectomy (LA) is the most common index procedure for junior surgical trainees. Despite the shift towards competency‐based training, there is no method of quantitatively assessing performance during LA. This study aimed to obtain expert consensus regarding the items required to create a LA Rating Scale (LARS).

Methods

A list of steps required for LA surgery, as well as descriptors of “poor”, “average” and “excellent” performance for each of these steps were created for potential inclusion into an objective assessment tool for LA surgery. Using a Delphi method, 20 experts from multiple institutions rated on a Likert scale from 1 to 5 the suitability of these steps and descriptors of performance. Responses were obtained until consensus (Cronbach's α > 0.8) was achieved.

Results

Fifteen experts participated in the study. Consensus was achieved for all items during the first iteration of the Delphi with a Cronbach's α of 0.96. The Cronbach's α for the steps was 0.87 and 0.92 for the descriptors of performance. Steps and descriptors of performance that >80% of experts rated as ≥4 were used to create the final LARS tool.

Conclusion

Multi‐institutional expert consensus was obtained regarding the steps and, for the first time, descriptors of performance for LA, demonstrating their face and content validity, as well as generalisability. Subsequently, the LARS tool was created that can be used to quantitatively assess intra‐operative performance. This instrument can be used to identify weaknesses in performance and facilitate deliberate practice, thus shifting training in LA to a competency‐based approach.

Guideline for the diagnosis and treatment of Faecal Incontinence-A UEG/ESCP/ESNM/ESPCG collaboration

INTRODUCTION

The goal of this project was to create an up-to-date joint European clinical practice guideline for the diagnosis and treatment of faecal incontinence (FI), using the best available evidence. These guidelines are intended to help guide all medical professionals treating adult patients with FI (e.g., general practitioners, surgeons, gastroenterologists, other healthcare workers) and any patients who are interested in information regarding the diagnosis and management of FI.

METHODS

These guidelines have been created in cooperation with members from the United European Gastroenterology (UEG), European Society of Coloproctology (ESCP), European Society of Neurogastroenterology and Motility (ESNM) and the European Society for Primary Care Gastroenterology (ESPCG). These members made up the guideline development group (GDG). Additionally, a patient advisory board (PAB) was created to reflect and comment on the draft guidelines from a patient perspective. Relevant review questions were established by the GDG along with a set of outcomes most important for decision making. A systematic literature search was performed using these review questions and outcomes as a framework. For each predefined review question, the study or studies with the highest level of study design were included. If evidence of a higher-level study design was available, no lower level of evidence was sought or included. Data from the studies were extracted by two reviewers for each predefined important outcome within each review question. Where possible, forest plots were created. After summarising the results for each review question, a systematic quality assessment using the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) approach was performed. For each review question, we assessed the quality of evidence for every predetermined important outcome. After evidence review and quality assessment were completed, recommendations could be formulated. The wording used for each recommendation was dependent on the level of quality of evidence. Lower levels of evidence resulted in weaker recommendations and higher levels of evidence resulted in stronger recommendations. Recommendations were discussed within the GDG to reach consensus.

RESULTS

These guidelines contain 45 recommendations on the classification, diagnosis and management of FI in adult patients.

CONCLUSION

These multidisciplinary European guidelines provide an up-to-date comprehensive evidence-based framework with recommendations on the diagnosis and management of adult patients who suffer from FI.

Validity and effectiveness of augmented reality in surgical education: A systematic review

BACKGROUND

Current challenges in surgical training have led to the investigation of augmented reality as a potential method of supplementary education. However, its value for this purpose remains uncertain. The aim of this study was to perform a systematic review of the published literature to evaluate the validity and effectiveness of augmented reality in surgical education, and to compare it with other simulation modalities.

METHODS

Electronic literature searches were performed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Two authors independently extracted pertinent data and assessed study quality. The primary outcome measures of interest were the validity and effectiveness of augmented reality as an educational tool.

RESULTS

Of 6,500 articles, 24 studies met eligibility criteria for inclusion, of which 2 were randomized. Ten studies investigated validity, with 7 establishing both face and content validity and an additional 1 just content validity. Construct validity was demonstrated in 9 of 11 studies. Of the 11 studies that examined the effectiveness of augmented reality in skills acquisition, 9 demonstrated enhanced learning. Of the 5 studies in which the effectiveness of augmented reality as an educational tool was compared with other modes of simulation, augmented reality was found to be superior in 2 and equivalent in the others.

CONCLUSION

Overall, the majority, including 2 high-quality randomized controlled trials, demonstrated the validity and effectiveness of augmented reality in surgical education. However, the quality of published studies was poor with marked heterogeneity. Although these results are encouraging, additional high-quality studies, preferably in the real-life environment, are required before the widespread implementation of augmented reality within surgical curricula can be recommended.

Patient-reported and physician-recorded bowel dysfunction following colorectal resection and radical cystectomy: a prospective, comparative study

AIM

Bowel dysfunction following anterior resection (AR) is termed low anterior resection syndrome. It is unclear whether such dysfunction occurs following other bowel/pelvic operations as well. This study aimed to characterize and compare bowel dysfunction following AR, right hemicolectomy (RH) and radical cystectomy (RC).

METHOD

A prospective study of consecutive patients undergoing AR, RH and RC (2002-2012) was performed at a tertiary referral centre in Sydney, Australia. Outcome measures included (i) patient-reported satisfaction with bowel function, self-described bowel function and self-reported change in bowel function; (ii) objective assessment of bowel function using validated criteria to identify symptoms and stratify patients into those with constipation and/or faecal incontinence (FI); and (iii) health-related quality of life (SF-36v2 Health Survey).

RESULTS

Of 743 eligible patients, 70% participated [AR, n = 338, mean age 69.6 years (SD 11.9), 59% men; RH, n = 150, 75.8 years (SD 10.5), 54% men; RC, n = 34, 71.1 years (SD 14.1), 71% men]. AR patients were three times more likely to report change in bowel function post-surgery and self-judged their bowel function as abnormal more frequently (64%) than RH patients (35%) and RC patients (35%) (P < 0.01). AR patients were four times more likely to meet criteria for concomitant constipation and FI. Patients with concomitant constipation and FI had lower physical and mental SF-36v2 scores (P < 0.001).

CONCLUSION

Bowel dysfunction occurred after RH and RC but rates were higher following AR. This suggests that low anterior resection syndrome occurs due to a direct impact of partial/complete loss of the rectum rather than just due to loss of bowel length and/or the consequence(s) of pelvic dissection.

Self-monitoring for recurrence of secondary atrial fibrillation following non-cardiac surgery or acute illness: A pilot study

Background

Atrial fibrillation (AF) secondary to non-cardiac surgery and medical illness is common and, although often transient, is associated with an increased risk of stroke and mortality. This pilot study tested the feasibility of self-monitoring to detect recurrent AF in this setting and the frequency with which it occurred.

Methods

Patients with new secondary AF after non-cardiac surgery or medical illness that reverted to sinus rhythm before discharge were recruited in three tertiary hospitals in Australia. Participants performed self-monitoring for AF recurrence using a Handheld single-lead ECG device 3–4 times/day for 4-weeks.

Results

From 16,454 admissions, 224 (1.4%) secondary AF cases were identified. Of these, 94 were eligible, and 29 agreed to participate in self-monitoring (66% male; median age 67 years). Self-monitoring was feasible and acceptable to participants in this setting. Self-monitoring identified AF recurrence in 10 participants (34%; 95% CI, 18% −54%), with recurrence occurring ≤ 9 days following discharge in 9/10 participants. Only 4 participants (40%) reported associated palpitations with recurrence. Six participants (60%) with recurrence had a CHA₂DS₂-VA score ≥ 2, suggesting a potential indication for oral anticoagulation.

Conclusions

Approximately 1 in 3 patients with transient secondary AF will have recurrent AF within nine days of discharge. These recurrent episodes are often asymptomatic but can be detected promptly using patient self-monitoring, which was feasible and acceptable. Future research is warranted to further investigate the incidence of secondary AF, the rate of recurrence after discharge and its prognosis, and whether use of oral anticoagulation can reduce stroke in this setting.

The microbiota-gut-brain axis: An emerging therapeutic target in chemotherapy-induced cognitive impairment

Chemotherapy-induced cognitive impairment (CICI) is an ill-defined complication of chemotherapy treatment that places a significant psychosocial burden on survivors of cancer and has a considerable impact on the activities of daily living. CICI pathophysiology has not been clearly defined, with candidate mechanisms relating to both the direct cytotoxicity of chemotherapy drugs on the central nervous system (CNS) and more global, indirect mechanisms such as neuroinflammation and blood brain barrier (BBB) damage. A growing body of research demonstrates that changes to the composition of the gastrointestinal microbiota is an initiating factor in numerous neurocognitive conditions, profoundly influencing both CNS immunity and BBB integrity. Importantly, chemotherapy causes significant disruption to the gastrointestinal microbiota. While microbial disruption is a well-established factor in the development of chemotherapy-induced gastrointestinal toxicities (largely diarrhoea), its role in CICI remains unknown, limiting microbial-based therapeutics or risk prediction strategies. Therefore, this review aims to synthesise and critically evaluate the evidence addressing the microbiota-gut-brain axis as a critical factor influencing the development of CICI.

Colonic transit in patients after anterior resection: prospective, comparative study using single-photon emission CT/CT scintigraphy

BACKGROUND

Bowel dysfunction after anterior resection is well documented, but its pathophysiology remains poorly understood. No study has assessed whether postoperative variation in colonic transit contributes to symptoms. This study measured colonic transit using planar scintigraphy and single-photon emission CT (SPECT)/CT in patients after anterior resection, stratified according to postoperative bowel function.

METHODS

Symptoms were assessed using the low anterior resection syndrome (LARS) score. Following gallium-67 ingestion, scintigraphy was performed at predefined time points. Nine regions of interest were defined, and geometric centre (GC), percentage isotope retained, GC velocity index and colonic half-clearance time (T_½ ) determined. Transit parameters were compared between subgroups based on LARS score using receiver operating characteristic (ROC) curve analyses.

RESULTS

Fifty patients (37 men; median age 72·6 (range 44·4-87·7) years) underwent planar and SPECT scintigraphy. Overall, 17 patients had major and nine had minor LARS; 24 did not have LARS. There were significant differences in transit profiles between patients with major LARs and those without LARS: GCs were greater (median 5·94 (range 2·35-7·72) versus 4·30 (2·12-6·47) at 32 h; P = 0·015); the percentage retained isotope was lower (median 53·8 (range 6·5-100) versus 89·9 (38·4-100) per cent at 32 h; P = 0·002); GC velocity indices were greater (median 1·70 (range 1·18-1·92) versus 1·45 (0·98-1·80); P = 0·013); and T_½ was shorter (median 38·3 (17·0-65·0) versus 57·0 (32·1-160·0) h; P = 0·003). Percentage tracer retained at 32 h best discriminated major LARS from no LARS (area under curve (AUC) 0·828).

CONCLUSION

Patients with major LARS had accelerated colonic transit compared with those without LARS, which may help explain postoperative bowel dysfunction in this group. The percentage tracer retained at 32 h had the greatest AUC value in discriminating such patients.

Quantification and neurochemical coding of the myenteric plexus in humans: No regional variation between the distal colon and rectum

BACKGROUND

It remains unclear whether regional variation exists in the human enteric nervous system (ENS) ie, whether intrinsic innervation varies along the gut. Recent classification of gastrointestinal neuropathies has highlighted inadequacies in the quantification of the human ENS. This study used paired wholemounts to accurately quantify and neurochemically code the hindgut myenteric plexus, comparing human distal colon and rectum.

METHODS

Paired human descending colonic/rectal specimens were procured from 15 patients undergoing anterior resection. Wholemounts of myenteric plexi were triple-immunostained with anti-Hu/NOS/ChAT antibodies. Images were acquired by motorized epifluorescence microscopy, allowing assessment of ganglionic density/size, ganglionic area density, and neuronal density. 'Stretch-corrected' values were calculated using stretched/relaxed tissue dimensions.

KEY RESULTS

Tile-stitching created a collage with average area 99 300 000 μm² . Stretch-corrected ganglionic densities were similar (colon: median 510 ganglia/100 mm² [range 386-1170], rectum: 585 [307-923]; P = .99), as were average ganglionic sizes (colon: 57 593 μm² [40 301-126 579], rectum: 54 901 [38 701-90 211], P = .36). Ganglionic area density (colon: 11.92 mm² per 100 mm² [7.53-18.64], rectum: 9.84 [5.80-17.19], P = .10) and stretch-corrected neuronal densities (colon: 189 neurons/mm² [117-388], rectum: 182 [89-361], P = .31) were also similar, as were the neurochemical profiles of myenteric ganglia, with comparable proportions of NOS+ and ChAT+ neurons (P > .10).

CONCLUSIONS AND INFERENCES

This study has revealed similar neuronal and ganglionic densities and neurochemical profiles in human distal colon and rectum. Further investigation of other components of the ENS, incorporating additional immunohistochemical markers are required to confirm that there is no regional variation in the human hindgut ENS.

Risk Factors in Acquired Faecal Incontinence

Acquired faecal incontinence arising in the non-elderly population is a common and often devastating condition. We conducted a retrospective cohort analysis in 629 patients (475 female) referred to a tertiary centre, to determine the relative importance of individual risk factors in the development of faecal incontinence, as demonstrated by abnormal results on physiological testing. Potential risk factors were identified in all but 6% of patients (7 female, 32 male). In women, the principal risk factor was childbirth (91%), and in most cases at least one vaginal delivery had met with complications such as perineal injury or the need for forceps delivery. Of the males, half had undergone anal surgery and this was the only identified risk factor in 59%. In many instances, assignment of cause was hampered by a long interval between the supposed precipitating event and the development of symptoms. Abnormalities of anorectal physiology were identified in 76% of males and 96% of females (in whom they were more commonly multiple). These findings add to evidence that occult damage to the continence mechanism, especially through vaginal delivery and anal surgery, can result in subsequent faecal incontinence, sometimes after an interval of many years.

Brain responses to mechanical rectal stimulation in patients with faecal incontinence: an fMRI study

AIM

Continence is dependent on anorectal-brain interactions. Consequently, aberrations of the brain-gut axis may be important in the pathophysiology of faecal incontinence (FI) in certain patients. The aim of this study was to assess the feasibility of recording brain responses to rectal mechanical stimulation in patients with FI using functional magnetic resonance imaging (fMRI).

METHOD

A prospective, cohort pilot study was performed to assess brain responses during rectal stimulation in 14 patients [four men, mean (SD) age 62 (15) years]. Blood oxygen level dependent (BOLD) signals were measured by fMRI during rest and mechanical distension, involving random repetitions of isobaric phasic rectal distensions at fixed (15 and 45 mmHg) and variable (10% above sensory perception threshold) pressures.

RESULTS

Increases in BOLD signals in response to high pressure rectal distension (45 mmHg) and maximum toleration were observed in the cingulate gyrus, thalamus, insular cortex, inferior frontal gyrus, cerebellum, caudate nucleus, supramarginal gyrus, putamen and amygdala. Additionally, activation of the supplementary motor cortex and caudate nucleus with inconsistent activity in the frontal lobe was observed.

CONCLUSIONS

This study has demonstrated the feasibility of recording brain responses to rectal mechanical stimulation using fMRI in patients with FI, revealing activity in widespread areas of the brain involved in visceral sensory processing. The observed activity in the supplementary motor cortex and caudate nucleus, with relative paucity of activity in the frontal lobes, warrants investigation in future studies to determine whether aberrations in cerebral processing of rectal stimuli play a role in the pathogenesis of FI.

Acute lower gastrointestinal haemorrhage: outcomes and risk factors for intervention in 949 emergency cases

PURPOSE

Outcomes of acute lower gastrointestinal haemorrhage (ALGIH) are mostly derived from studies performed in the sub-acute/elective rather than the emergency department (ED) setting. The aims of this study were to determine the incidence and outcomes of patients presenting to a tertiary hospital ED with ALGIH and to identify associated clinicopathological risk factors.

METHOD

A retrospective observational cohort study of consecutive patients presenting with ALGIH to a tertiary hospital ED was performed. Primary outcome measures included mortality and hospital (including high dependency [HDU]) admission. Secondary outcome measures included rates of (i) blood transfusion, (ii) radiological/endoscopic investigation(s) and (iii) therapeutic intervention.

RESULTS

ALGIH accounted for 949 (512 M, mean age 62.3 years) of 130,262 (0.73%) ED presentations, of which 285 patients (30.1%) were on anti-platelet/coagulant therapy. There were five deaths (0.5%). Hospital admission was required in 498 patients (52.5%), of which 19 (3.8%) required HDU monitoring. Hospital admission was twice as likely in males and four times more likely in patients >75 years old and those taking multiple anti-platelet/coagulant therapy (P < 0.05). Blood product transfusion was required in 172 patients (34.5%), specialist investigations in 230 (46.2%) and therapeutic intervention in 51 (10.2%) (surgery in 24 [4.8%]; endoscopic haemostasis in 20 [4.0%] and angiographic embolisation in 9 [1.8%] patients).

CONCLUSION

ALGIH accounts for 1% of all ED presentations, with half requiring hospital admission. Mortality and surgical intervention rates are low and although most patients can be managed supportively, access to interventional radiology/endoscopy is important.

Development of a proficiency-based virtual reality simulation training curriculum for laparoscopic appendicectomy

BACKGROUND

Proficiency-based virtual reality (VR) training curricula improve intraoperative performance, but have not been developed for laparoscopic appendicectomy (LA). This study aimed to develop an evidence-based training curriculum for LA.

METHODS

A total of 10 experienced (>50 LAs), eight intermediate (10-30 LAs) and 20 inexperienced (<10 LAs) operators performed guided and unguided LA tasks on a high-fidelity VR simulator using internationally relevant techniques. The ability to differentiate levels of experience (construct validity) was measured using simulator-derived metrics. Learning curves were analysed. Proficiency benchmarks were defined by the performance of the experienced group. Intermediate and experienced participants completed a questionnaire to evaluate the realism (face validity) and relevance (content validity).

RESULTS

Of 18 surgeons, 16 (89%) considered the VR model to be visually realistic and 17 (95%) believed that it was representative of actual practice. All 'guided' modules demonstrated construct validity (P < 0.05), with learning curves that plateaued between sessions 6 and 9 (P < 0.01). When comparing inexperienced to intermediates to experienced, the 'unguided' LA module demonstrated construct validity for economy of motion (5.00 versus 7.17 versus 7.84, respectively; P < 0.01) and task time (864.5 s versus 477.2 s versus 352.1 s, respectively, P < 0.01). Construct validity was also confirmed for number of movements, path length and idle time. Validated modules were used for curriculum construction, with proficiency benchmarks used as performance goals.

CONCLUSION

A VR LA model was realistic and representative of actual practice and was validated as a training and assessment tool. Consequently, the first evidence-based internationally applicable training curriculum for LA was constructed, which facilitates skill acquisition to proficiency.

Electrophysiological characterization of human rectal afferents

It is presumed that extrinsic afferent nerves link the rectum to the central nervous system. However, the anatomical/functional existence of such nerves has never previously been demonstrated in humans. Therefore, we aimed to identify and make electrophysiological recordings in vitro from extrinsic afferents, comparing human rectum to colon. Sections of normal rectum and colon were procured from anterior resection and right hemicolectomy specimens, respectively. Sections were pinned and extrinsic nerves dissected. Extracellular visceral afferent nerve activity was recorded. Neuronal responses to chemical [capsaicin and "inflammatory soup" (IS)] and mechanical (Von Frey probing) stimuli were recorded and quantified as peak firing rate (range) in 1-s intervals. Twenty-eight separate nerve trunks from eight rectums were studied. Of these, spontaneous multiunit afferent activity was recorded in 24 nerves. Peak firing rates increased significantly following capsaicin [median 6 (range 3-25) spikes/s vs. 2 (1-4), P < 0.001] and IS [median 5 (range 2-18) spikes/s vs. 2 (1-4), P < 0.001]. Mechanosensitive "hot spots" were identified in 16 nerves [median threshold 2.0 g (range 1.4-6.0 g)]. In eight of these, the threshold decreased after IS [1.0 g (0.4-1.4 g)]. By comparison, spontaneous activity was recorded in only 3/30 nerves studied from 10 colons, and only one hot spot (threshold 60 g) was identified. This study confirms the anatomical/functional existence of extrinsic rectal afferent nerves and characterizes their chemo- and mechanosensitivity for the first time in humans. They have different electrophysiological properties to colonic afferents and warrant further investigation in disease states.

Building a sustainable clinical academic workforce to meet the future healthcare needs of Australia and New Zealand: report from the first summit meeting

The delivery of healthcare that meets the requirements for quality, safety and cost-effectiveness relies on a well-trained medical workforce, including clinical academics whose career includes a specific commitment to research, education and/or leadership. In 2011, the Medical Deans of Australia and New Zealand published a review on the clinical academic workforce and recommended the development of an integrated training pathway for clinical academics. A bi-national Summit on Clinical Academic Training was recently convened to bring together all relevant stakeholders to determine how best to do this. An important part understood the lessons learnt from the UK experience after 10 years since the introduction of an integrated training pathway. The outcome of the summit was to endorse strongly the recommendations of the medical deans. A steering committee has been established to identify further stakeholders, solicit more information from stakeholder organisations, convene a follow-up summit meeting in late 2015, recruit pilot host institutions and engage the government and future funders.

Outcomes of support rod usage in loop stoma formation

AIM

Traditionally, support rods have been used when creating loop stomas in the hope of preventing retraction. However, their effectiveness has not been clearly established. This study aimed to investigate the rate of stoma rod usage and its impact on stoma retraction and complication rates.

METHOD

A prospective cohort of 515 consecutive patients who underwent loop ileostomy/colostomy formation at a tertiary referral colorectal unit in Sydney, Australia were studied. Mortality and unplanned return to theatre rates were calculated. The primary outcome measure of interest was stoma retraction, occurring within 30 days of surgery. Secondary outcome measures included early stoma complications. The 10-year temporal trends for rod usage, stoma retraction, and complications were examined.

RESULTS

Mortality occurred in 23 patients (4.1 %) and unplanned return to theatre in 4 patients (0.8 %). Stoma retraction occurred in four patients (0.78 %), all without rods. However, the rate of retraction was similar, irrespective of whether rods were used (P = 0.12). There was a significant decline in the use of rods during the study period (P < 0.001) but this was not associated with an increase in stoma retraction rates. Early complications occurred in 94/432 patients (21.8 %) and were more likely to occur in patients with rods (64/223 versus 30/209 without rods, P < 0.001).

CONCLUSIONS

Stoma retraction is a rare complication and its incidence is not significantly affected by the use of support rods. Further, complications are common post-operatively, and the rate appears higher when rods are used. The routine use of rods warrants judicious application. WHAT DOES THIS PAPER ADD TO THE LITERATURE?: It remains unclear whether support rods prevent stoma retraction. This study, the largest to date, confirms that stoma retraction is a rare complication and is not significantly affected by the use of rods. Consequently, routine rod usage cannot be recommended, particularly as it is associated with increased stoma complications.

Systematic review of the impact of sacral neuromodulation on clinical symptoms and gastrointestinal physiology

Background

Sacral neuromodulation (SNM) has emerged as a treatment option for faecal incontinence (FI). However, its objective effect on symptoms and anorectal function is inconsistently described. This study aimed to systematically review the impact of SNM on clinical symptoms and gastrointestinal physiology in patients with FI, including factors that may predict treatment outcome.

Methods

An electronic search of MEDLINE (1946–2014)/EMBASE database was performed in accordance with PRISMA guidelines. Articles that reported the relevant outcome measures following SNM were included. Clinical outcomes evaluated included: frequency of FI episodes, FI severity score and success rates. Its impact on anorectal and gastrointestinal physiology was also evaluated.

Results

Of 554 citations identified, data were extracted from 81 eligible studies. Meta‐analysis of the data was precluded due to lack of a comparison group in most studies. After permanent SNM, ‘perfect’ continence was noted in 13–88% of patients. Most studies reported a reduction in weekly FI episodes (median difference of the mean −7.0 (range: −24.8 to −2.7)) and Wexner scores (median difference of the mean −9 (−14.9 to −6)). A trend towards improved resting and squeeze anal pressures and a reduction in rectal sensory volumes were noted. Studies failed to identify any consistent impact on other physiological parameters or clinicophysiological factors associated with success.

Conclusion

SNM improves clinical symptoms and reduces number of incontinence episodes and severity scores in patients with FI, in part by improving anorectal physiological function. However, intervention studies with standardized outcome measures and physiological techniques are required to robustly assess the physiological impact of SNM.

Evacuation proctography: a reappraisal of normal variability

AIM

Interpretation of evacuation proctography (EP) images is reliant on robust normative data. Previous studies of EP in asymptomatic subjects have been methodologically limited. The aim of this study was to provide parameters of normality for both genders using EP.

METHOD

Evacuation proctography was prospectively performed on 46 healthy volunteers (28 women). Proctograms were independently analysed by two reviewers. All established and some new variables of defaecatory structure and function were assessed objectively: anorectal dimensions; anorectal angle changes; evacuation time; percentage contrast evacuated; and incidence of rectal wall morphological 'abnormalities'.

RESULTS

Normal ranges were calculated for all main variables. Mean end-evacuation time was 88 s (95% CI: 63-113) in male subjects and 128 s (95% CI: 98-158) in female subjects; percentage contrast evacuated was 71% (95% CI: 63-80) in male subjects and 65% (95% CI: 58-72) in female subjects. Twenty-six (93%) of 28 female subjects had a rectocoele with a mean depth of 2.5 cm (upper limit = 3.9 cm). Recto-rectal intussusception was found in nine subjects (approximately 20% of both genders); however, recto-anal intussusception was not observed. Only rectal diameter differed significantly between genders. Qualitatively, three patterns of evacuation were present.

CONCLUSION

This study defines normal ranges for anorectal dimensions and parameters of emptying, as well as the incidence and characteristics of rectal-wall 'abnormalities' observed or derived from EP. These ranges can be applied clinically for subsequent disease comparison.

Neuroanatomy and physiology of colorectal function and defaecation: from basic science to human clinical studies

Colorectal physiology is complex and involves programmed, coordinated interaction between muscular and neuronal elements. Whilst a detailed understanding remains elusive, novel information has emerged from recent basic science and human clinical studies concerning normal sensorimotor mechanisms and the organization and function of the key elements involved in the control of motility. This chapter summarizes these observations to provide a contemporary review of the neuroanatomy and physiology of colorectal function and defaecation.

Pathophysiology of evacuation disorders

This review details our contemporary knowledge of the mechanisms underlying evacuatory disorders. There is confusion concerning terminology and classification, which is based upon both an incomplete understanding of the multiple mechanisms involved in evacuation, and that current tests to investigate it are not physiological. Nevertheless, despite the need for more research, significant advances have been made and current assessments can direct therapy.

Rectal hyposensitivity: pathophysiological mechanisms

Rectal hyposensitivity (RH) relates to a diminished perception of rectal distension. It may occur due to afferent nerve dysfunction and/or secondary to abnormal structural or biomechanical properties of the rectum. The aim of this study was to determine the contribution of these underlying pathophysiological mechanisms by systematically evaluating rectal diameter, compliance and afferent nerve sensitivity in patients with RH, using methodology employed in clinical practice. The study population comprised 45 (33 women; median age 48, range 25-72 years) constipated patients (Rome II criteria) with RH and 20 with normal rectal sensitivity on balloon distension and 20 healthy volunteers. Rectal diameter was measured at minimum distending pressure during isobaric distension under fluoroscopic screening. Rectal compliance was assessed during phasic isobaric distension by measuring the slope of the pressure-volume curve. Electrical stimulation of the rectal mucosa was employed to determine afferent nerve function. Values were compared to normal ranges established in healthy volunteers. The upper limits of normal for rectal diameter, compliance and electrosensitivity were 6.3 cm, 17.9 mL mmHg(-1) and 21.3 mA respectively. Among patients with RH, rectal diameter, but not compliance, was increased above the normal range (megarectum) in seven patients (16%), two of whom had elevated electrosensitivity thresholds. Rectal diameter and compliance were elevated in 23 patients (51%), nine of whom had elevated electrosensitivity thresholds. The remaining 15 patients (33%) with RH had normal rectal compliance and diameter, all of whom had elevated electrosensitivity thresholds. Two-third of the patients with RH on simple balloon distension have elevated rectal compliance and/or diameter, suggesting that impaired perception of rectal distension is due to inadequate stimulation of the rectal afferent pathway. However, a proportion of such patients also appear to have impaired nerve function. In the remaining one-third of the patients, rectal diameter and compliance are normal, while electrosensitivity thresholds are elevated, suggestive of true impaired afferent nerve function. Identification of these subgroups of patients with RH may have implications regarding their management.

Surgical treatment of patients with constipation and fecal incontinence

Patients with constipation and fecal incontinence usually come to the attention of the surgeon when conservative measures have failed to alleviate sufficiently severe symptoms. Following detailed clinical and physiologic assessment, the surgeon should tailor the procedure to specific underlying physiologic abnormalities to restore function. This article describes the rationale, indications (including patient selection), results, and current position controversies of surgical procedures for constipation and fecal incontinence, dividing these into those regarded as historical, contemporary, or evolving. Reported surgical outcome data must be interpreted with caution because for most studies the evidence is of low quality, making comparison of different procedures problematic and emphasizing the need for better designed and conducted clinical trials.

Manometric, sensorimotor, and neurophysiologic evaluation of anorectal function

With advances in diagnostic technology, it is now accepted that in the field of functional bowel disorders, symptom-based assessment is unsatisfactory as the sole means of directing therapy. A robust taxonomy based on underlying pathophysiology has been suggested, highlighting a crucial role for physiologic testing in clinical practice. A wide number of complementary investigations currently exist for the assessment of anorectal structure and function, some of which have a clinical impact in patients with functional disorders of evacuation and continence by markedly improving diagnostic yield and altering management. The techniques, limitations, measurements, and clinical use of manometric, sensorimotor, and neurophysiologic tests of anorectal function are presented.

Novel concepts in the diagnosis, pathophysiology and management of idiopathic megabowel

A proportion of patients with intractable constipation have persistent dilatation of the bowel, which in the absence of an organic cause is termed idiopathic megabowel (IMB). Whilst uncommon, this condition results in considerable morbidity. Traditional methods of identifying such patients are associated with inherent methodological limitations with anorectal manometry and contrast studies overestimating and underestimating the prevalence of the condition, respectively. Recently, controlled, pressure-based distension during fluoroscopic imaging has allowed more accurate identification of patients on the basis of a rectal diameter > 6.3 cm at the minimum distension pressure. Histopathological abnormalities of all three final effectors of sensorimotor function have been reported, although it remains unclear whether these changes are primary, secondary or epiphenomic. Physiological abnormalities of sensorimotor function, namely impaired perception of rectal distension and delayed colonic transit are well documented in patients with IMB. Further, the recent demonstration of two subgroups of patients, defined on the basis of rectal compliance, suggests the possibility that they differ pathophysiologically, although the clinical relevance of this distinction is uncertain. Surgery is performed when conservative therapy is ineffective or poorly tolerated. Numerous procedures have been attempted with variable success rates and significant mortality and morbidity. Surgery should preferably be performed in specialist centres given the relative infrequency with which such patients are encountered, and that they require comprehensive clinical, psychological and physiological evaluation preoperatively.

In patients with slow transit constipation, the pattern of colonic transit delay does not differentiate between those with and without impaired rectal evacuation

BACKGROUND

Severe constipation may be subclassified on the basis of speed of colonic transit and efficacy of rectal evacuation. It is hypothesized that rectal evacuatory disorder (RED) may be associated with a secondary transit delay.

OBJECTIVES

To determine whether scintigraphy can discriminate between slow transit constipation (STC) with or without coexistent RED on the basis of progression of isotope throughout the colon and by analyses of specific regions of interest.

METHODS

One hundred ninety-six patients with STC (radio-opaque marker study) were subclassified according to results of proctography into those with a RED (STC-RED N = 30) or normal (STC-ONLY N = 41) evacuation. Patients subsequently underwent colonic scintigraphy. Distribution of generalized or left-sided patterns of colonic transit was assessed. Severities of transit delay and regional transit at specific time points were also evaluated.

RESULTS

Time-activity curves and severity of global transit delay were similar between groups as were the incidences of generalized and left-sided patterns of delay. Percentage of radioisotope retention in the right colon at 18 h was higher for the STC-ONLY group (P < 0.05), but this was poorly discriminative. No differences were observed for the percentage of radioisotope retained in the left colon at later scans.

CONCLUSIONS

Global and regional assessment of colonic transit by scintigraphy failed to discriminate between patients with STC with or without coexistent RED. Thus, RED is not associated with a specific pattern of transit delay and scintigraphy alone cannot predict the presence or absence of RED, knowledge of which is important for management.

Rectal hyposensitivity: evaluation of anal sensation in female patients with refractory constipation with and without faecal incontinence

Rectal hyposensitivity (RH) is commonly found in patients with intractable constipation, faecal incontinence or both. Anal sensation may also be blunted in these conditions. We aimed to determine whether RH is associated with anal hyposensitivity, which may reflect a combined viscero-somatic neuropathy. One hundred and fifty-eight female patients with chronic constipation underwent physiological investigation including rectal sensation to volumetric balloon distension, and distal anal mucosal sensation to electrostimulation. Data were also obtained from 32 healthy female volunteers. Anal mucosal electrosensory thresholds were significantly higher in patients compared with volunteers (median: 2.4 mA, range: 0.4-19.6 vs 1.1 mA, range: 0.1-4.2, respectively), although the patient group was older (P < 0.0001), but there was no difference (P = 0.572) in the incidence of blunted anal sensation between those with normal rectal sensation (n = 113, 20% abnormal) and RH (n = 45, 24% abnormal). Irrespective of rectal sensory function, there was a strong association between symptom duration (P = 0.012) and anal hyposensitivity. One-fifth of constipated female patients had evidence of diminished anal sensation. However, the presence of RH was not associated with an increased frequency of anal hyposensitivity, thereby suggesting that different aetiopathogenic mechanisms underlie the development of anal and rectal hyposensitivity. Further studies in carefully selected, homogenous patient populations are necessary to elucidate these mechanisms.

Faecal incontinence (Br J Surg 2007; 94: 134–144)

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A novel technique to identify patients with megarectum

PURPOSE

Traditional methods of identifying patients with persistent dilation of the rectum, or megarectum, are associated with inherent methodologic limitations. The purpose of this study was to use a barostat to establish criteria for the diagnosis of megarectum and to assess rectal diameter during isobaric (barostat) and volumetric (barium contrast) distention protocols in constipated patients with megarectum on anorectal manometry.

METHODS

During fluoroscopic screening, rectal diameter was measured at minimum distending pressure of the rectum, achieved using a barostat. It was also measured during evacuation proctography (volumetric distention). Having established a normal range in 25 healthy volunteers, 30 constipated patients with evidence of megarectum on anorectal manometry (elevated maximum tolerable volume on latex balloon distention) were studied. A further 10 constipated patients without evidence of megarectum were studied (normal rectum).

RESULTS

Megarectum was diagnosed when the rectal diameter was greater than 6.3 cm at minimum distending pressure. Rectal diameter at minimum distending pressure was increased in 20 patients (67 percent) with megarectum on anorectal manometry, but was normal in the remaining 10 patients (33 percent) and all patients with a normal rectum on anorectal manometry. Rectal diameter was increased at evacuation proctography in only 15 patients (50 percent) with evidence of megarectum on anorectal manometry.

CONCLUSIONS

The prevalence of megarectum is overestimated and underestimated when rectal diameter is assessed using anorectal manometry and contrast studies, respectively. Controlled (pressure-based) distention combined with fluoroscopic imaging allowed accurate identification of patients with megarectum on the basis of a rectal diameter greater than 6.3 cm at the minimum distention pressure. Measurement of rectal diameter at minimum distention pressure may be useful in those patients with an elevated maximum tolerable volume on anorectal manometry when surgery is being contemplated.